well it isnt so much of journey, as i dont game much
basically the only new games i ve played are hogwarts game and baldurs gate 3 and little bit of elden ring.. pretty much all other games i played is just indie or low graphic games
for me they all look and work fine, but i dont know much about game performance or graphics quality and have no other to compare to than ps4, so you might need to see some youtube videos or something about that
i also dont play any competitive games, other than AOM, but dat is from 2000s.. so…
i have used its desktop, but mainly for watching videos. its basic kde desktop with some theme changes.. the programs are installed as flatpak because the root filesystem is immutable. so you are supposed to install all applications from UI, discover app.. the updates are similar, you just press the update..
i also have the steam deck dock, so i can connect it to pc scren, keyboard, mouse, etc. but i havent needed or used it that much..
all in all for my use case its perfect.. but thats partly because i really liked gnu linux.. i feel like the life span of such device is so much longer when the software is hackable, but if you are concerned about how it runs particular games, you should first check the videos about it..